Acoustic homing torpedo

ABSTRACT

11. The device of claim 8 wherein the velocity of sound transmission in the explosive material is substantially equal to the velocity of sound transmission in seawater, THE REAR SURFACE OF THE EXPLOSIVE MATERIAL HAS THE SHAPE OF A PARABOLA AND IS CONTACTED BY A SOUND WAVE REFLECTOR HAVING THE CONTOUR OF A PARABOLOID, SAID TRANSDUCERS BEING POSITIONED IN THE FOCAL PLANE OF THE REFLECTOR.

United States Patent 1 11 3,728,982 Dunlap Apr. 24, 1973 [54] ACOUSTIC HOMING TORPEDO 2.451502 11/1948 Dimmick ..340/8 RT Inventor: Richard M. p Middletown, 2,145,679 8/1964 Brooks ..ll4/23 Primary Examiner-Samuel Feinberg [73] Assignee: The United States of America as Assistant E i j 1 represented by the Seeretary 0f the Att0rney-Q. 8. Warner, R. F. Hossfeld and R. J. y Erickson [22] Filed: June 15, 1964 Appl. No.: 376,299

U.S. Cl. ..ll4/23, 114/21, 340/8 L, 340/8 FT, 340/6 R Int. Cl ..F42b 19/00, GOlv 1/00 Field of Search ..114/23, 21; 340/6, 340/8, 9; 244/143 References Cited UNITED STATES PATENTS 10/ 1 948 Peterson ..340/8 RT EXEMPLARY CLAIM 11. The device of claim 8 wherein the velocity of sound transmission in the explosive material is substantially equal to the velocity of sound transmission in seawater,

the rear surface of the explosive material has the shape of a parabola and is contacted by a sound wave reflector having the contour of a paraboloid, said transducers being positioned in the focal plane of the reflector.

11 Claims, 3 Drawing Figures PATENTEDAPRM ma 3,728,982

N 2 U LL I LL.

Richard Morris Dunlap mvsmoa ATTORNEY.

ACOUSTIC HOMING TORPEDO The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to an improved acoustic homing torpedo and more specifically to a homing torpedo wherein the explosive charge is located in the forwardmost portion of the torpedo and has the acoustic target sensing elements embedded directly therein.

An acoustic homing torpedo requires a plurality of acoustic target sensing transducers or hydrophones, generally four in number and arranged in quadrature about the longitudinal axis of the torpedo, which are electrically connected to a steerage control system which guides the torpedo as it travels through the water to the target. In conventional acoustic homing torpedos, it has been the practice to mount the hydrophones in the nose of the torpedo and to locate the explosive charge or warhead behind said hydrophones so that the explosive charge does not interfere with the reception of acoustic signals emanating from the target by the hydrophones'. Because the explosive charge is spaced an appreciable distance from the nose of the torpedo to permit positioning of the hydrophones within the forwardmost portion of the torpedo, when the torpedo makes contact with the target, a substantial portion of the energy from the explosive charge is dissipated into the water and is not directed upon the target due to the fact that the explosive charge is spaced from the target. It is of course most desirable to have the explosive material located at the forwardmost portion of the torpedo so that, upon impact with the target, the explosive will be in direct contact with the hull of the target vessel and thereby enable the torpedo to inflict its maximum amount of damage to the target vessel. It has also been the practice in the manufacture of acoustic homing torpedoes to mount the hydrophones in such a manner as to involve the use of outward projections formed upon the nose of the torpedo or other surface irregularities required in the mounting of the hydrophones which adversely effect the hydrodynamic shape of the torpedo and its smooth travel through the water.

The present invention eliminates the disadvantages of the prior systems yet retains all of the advantages characteristic thereof. The present invention provides an acoustic homing torpedo having the explosive charge located in the forwardmost portion of the torpedo, i.e. directly in the nose of the torpedo, and has the hydrophones embedded directly in the explosive material and symmetrically arranged in quadrature about the longitudinal axis of the torpedo and being equidistan tly spaced therefrom. Two of the acoustic target sensing transducers or hydrophones are disposed on either side of the longitudinal axis of the torpedo in the normal horizontal plane of the torpedo and the other two hydrophones are disposed in the normal vertical plane above and below the longitudinal axis of the torpedo. The explosive material acts as a convex lens to focus acoustic signals emanating from a target upon the hydrophones and these hydrophones are electrically connected to a steerage control system, the steerage control system being of conventional nature and not forming a part of this invention. The positioning of the explosive material in the forwardmost portion of the torpedo enables the explosive material to inflict its maximum amount of damage upon the target when the torpedo makes contact with the target; and the positioning of the transducers within the explosive material eliminates any surface irregularities in the outer surface of the torpedo and thereby maintains the optimum hydrodynamic shape of the torpedo.

In accordance with the foregoing, it is an object of the present invention to provide an acoustic homing torpedo having the explosive material positioned in the forwardmost portion of the torpedo.

Another object of the invention is to provide a homing torpedo wherein the components thereof are arranged in such a manner as to enable the torpedo to have a greater destructive capability than conventional homing torpedoes without an increase in explosive material or alternatively to produce the same amount of destructive capability as the conventional torpedo with a lesser amount of explosive material.

A further object of the invention is to provide an acoustic homing torpedo having the explosive material positioned in the nose thereof to form a lens for focusing acoustic signals upon the hydrophones mounted within the explosive material to thereby increase the lethal capabilities of the torpedo and to improve the hydrodynamic shape of the torpedo.

Other objects and many of the attendant advantages of the present invention will become apparent in light of the following detailed description thereof and the annexed drawings wherein:

FIG. 1 illustrates an elevational view taken partially in section of an acoustic homing torpedo incorporating the principles of the present invention;

FIG. 2 illustrates a sectional view of the nose portion of a torpedo according to another embodiment of the present invention; and

FIG. 3 illustrates a sectional view of the nose cone of FIG. 1 taken along line 3--3.

In FIG. 1, there is shown an elongated cylindrical torpedo 11 having a convex nose portion 12 and a conically shaped tail section 13 upon which are pivotally mounted a pair of driving propellers l4. Fixedly mounted upon the exterior surface of the conical tail section is a pair of vertical fins 15 and I6 oppositely disposed on either side of the torpedo in a vertical plane passing through the longitudinal axis of the torpedo. Pivotally mounted upon the fins l5 and 16, are a pair of rudders l7 and 18 which are mechanically coupled to a control means within the torpedo for steering the torpedo to the right or left as it travels through the water. Also mounted upon the exterior surface of the tail section of the torpedo, is a pair of stabilizers 19 which are oppositely disposed on either side of the torpedo in a plane perpendicular to the plane of said fins signals to selectively control the elevators and rudders by means of mechanical links 23 and 24 connected therebetween. The steerage control system forms no part of the present invention and any suitable steering control system may be employed for the purposes of this invention. One such system, for example, is disclosed and claimed in the US. Pat. No. 2,987,025 issued on June 6, 1961 to R.A. Cunningham. The mass of explosive material comprising the warhead of the torpedo is positioned within and completely fills the nose and forward portion of the torpedo. The particular explosive employed may be any one of a large number of well known explosives having a velocity of sound trans mission which is slower than the velocity of sound transmission through water. By using an explosive having such characteristics, the mass of explosive material acts like a plano-convex lens and, as an approaching incident sound wave, shown at 26 in the drawings, approaches the convex nose of the torpedo, the sound wave will be refracted and will be focused along the dotted lines shown in the drawing upon a focal point within the lens of explosive material onto an acoustic target sensing transducer 27. Four such acoustic target sensing transducers or hydrophones are embedded in the explosive material and are arranged in quadrature within the focal plane of the plane-convex lens. As shown in FIG. 3 two of the acoustic target sensing transducers 27 and 28 are disposed in the normal vertical plane of the torpedo on opposite sides of the longitudinal axis of the torpedo and are equidistant therefrom while the other two transducers 30 and 31 are disposed in the normal horizontal plane of the torpedo on either side of the longitudinal axis of the torpedo and equidistant therefrom. The four transducers are electrically connected to the steerage control system 22 which processes and compares the signals received from each of the transducers and controls the rudders and elevators to guide the torpedo toward the target. If the acoustic sound wave emanating from the target is aligned with the longitudinal axis of the torpedo, the signals derived from the four transducers will be equal and the steerage control system will maintain the torpedo on its present course. If however, the sound wave emanating from the target approaches from an angle to the longitudinal axis of the torpedo, the signals generated by the four transducers will be unequal and the steerage control system will operate to turn either the elevators or the rudders to alter the course of the torpedo and direct it toward the target. By positioning the explosive material within the nose and forward portion of the torpedo and embedding the transducers therein, it is seen that the explosive material serves a dual function, i.e. to form the torpedo warhead as well as to form the sensing head for the homing system. By embedding the transducers within the explosive material, the external surface of the torpedo is free of any surface irregularities and therefore the torpedo has a clean hydrodynamic shape and is permitted to travel smoothly through the water. Additionally, since the intensity of a shock wave produced by an explosive varies inversely with the square of the distance from the origin of the explosion, it is readily apparent that the torpedo constructed in the manner of the present invention is capable of inflicting a greater amount of damage to a target vessel with a given amount of explosive material than would be a conventional torpedo. By placing the explosive material in the nose and forward portion of the torpedo and embedding the transducers therein, the amount of space normally occupied by the hydrophones in a conventional torpedo is eliminated and the killing power of the torpedo is increased because the warhead is closer to the target upon detonation and these two factors, therefore, make it possible to either increase the killing power of a torpedo with the same amount of explosive without increasing the size of the torpedo or alternatively to reduce the size of the torpedo without sacrificing the destructive capabilities thereof.

Under certain circumstances, it may be desirable to provide the torpedo with a concave sound reflector 29, as shown in FIG. 2, which contacts the rear surface of the explosive material and focuses the sound wave upon the hydrophones. For example, if the focal length of the lens is sufiiciently long as to require a mass of explosive material greater than that needed to destroy a target vessel, the torpedo may be provided with a concave metallic sound reflector of suitable thickness and having the configuration of a hyperboloid and being positioned within the torpedo in abutting contact with the rear surface of the explosive material to thereby reflect the sound wave forwardly onto the hydrophones. When the reflector is used in the torpedo of this invention, the hydrophones are positioned in the focal plane of the reflector rather than in the focal plane of the lens.

A sound reflector may also be provided for the lens when it is desired to use explosives in the torpedo which have velocities of sound transmission which are either equal to or greater than the velocity of sound transmission in seawater. If the particular explosive material to be used in the torpedo has a sound transmission velocity equal to that of seawater, for example, a sound wave from a target will not be refracted by the interface of the convex nose of the torpedo and seawater but will continue to travel through the explosive in a straight line. When such an explosive material is used as the warhead, the concave reflector 29 is designed to have the contour of a paraboloid and'will therefore reflect and focus the sound wave upon the hydrophones which are positioned in the focal plane of the reflector.

If the particular material making up the warhead has a velocity of sound transmission greater than seawater, an incident sound wave arriving at the interface of the lens and the seawater will be refracted and caused to take a divergent path as it enters the explosive material. When such explosives are used, the concave reflector 29 is designed to have the configuration of an ellipsoid and will consequently reflect and refocus the reflected sound wave upon the hydrophones located in the focal plane of the reflector. As seen from the description of the reflector, selection of an appropriate reflector for the torpedo of the present invention permits the use of nearly any explosive material as the warhead.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A homing torpedo comprising an elongated cylindrical vessel having a convex nose portion at the forward end thereof,

a propeller mounted externally on the after end of the vessel and being connected to a motor within the vessel for propelling the vessel,

a mass of explosive material positioned within and completely filling the nose of the vessel to define a convex lens,

a plurality of hydrophones embedded in said lens for generating electrical signals upon the reception of a sound wave,

steerage control means electrically connected to the hydrophones for processing and comparing said signals, and

a rudder and an elevator mounted on said vessel and connected to said control means and actuated thereby to control the direction and depth of travel of the torpedo toward a target in response to said signals.

2. The device of claim 1 wherein the lens is a planoconvex lens and the hydrophones are orthogonally spaced apart in the focal plane of the lens and equidistant from the longitudinal axis of said lens.

3. The device of claim 2 wherein the explosive material is characterized by a lower sound transmission velocity than seawater.

4. The device of claim 1 further comprising,

a concave sound wave reflector positioned within the vessel in intimate contact with the rear surface of the lens, and

the hydrophones are positioned in the focal plane of the reflector.

5. The device of claim 4 wherein the explosive material has a velocity of sound transmission less than seawater,

and the reflector has the configuration of a hyperboloid.

6. The device of claim 4 wherein the explosive material has a velocity of sound wave transmission greater than seawater, and

the reflector has the configuration of an ellipsoid.

7. The device of claim 4 wherein the explosive material has a velocity of sound transmission substantially equal to that of seawater, and

the reflector has the configuration of a paraboloid.

8. An acoustic sensing assembly for a torpedo, comprising a cylindrical shell having one end thereof closed by a convex wall and being adopted for use as the forward portion of a torpedo,

a mass of explosive material disposed within and filling said shell to form a convex lens for receiving and focusing sound waves emanating from a target vessel,

four piezolectric transducers embedded in said explosive material, two of the transducers forming azimuth sensing units and the other two transducers forming zenith sensing units,

said transducers being orthogonally spaced apart equidistant from the longitudinal axis of the lens.

9. The device of claim 8 wherein the velocity of sound transmission in the explosive material is less than in seawater, and

said transducers are embedded in the explosive material in the focal plane of the lens. 10. The device of claim 8 wherein the velocity of sound transmission in the explosive material is greater than in seawater, and

the rear surface of the mass of explosive material is encased by a sound wave reflector having the configuration of an ellipsoid and the transducers are positioned in the focal plane of the reflector.

11. The device of claim 8 wherein the velocity of sound transmission in the explosive material is substantially equal to the velocity of sound transmission in seawater,

the rear surface of the explosive material has the shape of a parabola and is contacted by a sound wave reflector having the contour of a paraboloid, said transducers being positioned in the focal plane of the reflector. 

1. A homing torpedo comprising an elongated cylindrical vessel having a convex nose portion at the forward end thereof, a propeller mounted externally on the after end of the vessel and being connected to a motor within the vessel for propelling the vessel, a mass of explosive material positioned within and completely filling the nose of the vessel to define a convex lens, a plurality of hydrophones embedded in said lens for generating electrical signals upon the reception of a sound wave, steerage control means electrically connected to the hydrophones for processing and comparing said signals, and a rudder and an elevator mounted on said vessel and connected to said control means and actuated thereby to control the direction and depth of travel of the torpedo toward a target in response to said signals.
 1. A homing torpedo comprising an elongated cylindrical vessel having a convex nose portion at the forward end thereof, a propeller mounted externally on the after end of the vessel and being connected to a motor within the vessel for propelling the vessel, a mass of explosive material positioned within and completely filling the nose of the vessel to define a convex lens, a plurality of hydrophones embedded in said lens for generating electrical signals upon the reception of a sound wave, steerage control means electrically connected to the hydrophones for processing and comparing said signals, and a rudder and an elevator mounted on said vessel and connected to said control means and actuated thereby to control the direction and depth of travel of the torpedo toward a target in response to said signals.
 2. The device of claim 1 wherein the lens is a plano-convex lens and the hydrophones are orthogonally spaced apart in the focal plane of the lens and equidistant from the longitudinal axis of said lens.
 3. The device of claim 2 wherein the explosive material is characterized by a lower sound transmission velocity than seawater.
 4. The device of claim 1 further comprising, a concave sound wave reflector positioned within the vessel in intimate contact with the rear surface of the lens, and the hydrophones are positioned in the focal plane of the reflector.
 5. The device of claim 4 wherein the explosive material has a veLocity of sound transmission less than seawater, and the reflector has the configuration of a hyperboloid.
 6. The device of claim 4 wherein the explosive material has a velocity of sound wave transmission greater than seawater, and the reflector has the configuration of an ellipsoid.
 7. The device of claim 4 wherein the explosive material has a velocity of sound transmission substantially equal to that of seawater, and the reflector has the configuration of a paraboloid.
 8. An acoustic sensing assembly for a torpedo, comprising a cylindrical shell having one end thereof closed by a convex wall and being adopted for use as the forward portion of a torpedo, a mass of explosive material disposed within and filling said shell to form a convex lens for receiving and focusing sound waves emanating from a target vessel, four piezolectric transducers embedded in said explosive material, two of the transducers forming azimuth sensing units and the other two transducers forming zenith sensing units, said transducers being orthogonally spaced apart equidistant from the longitudinal axis of the lens.
 9. The device of claim 8 wherein the velocity of sound transmission in the explosive material is less than in seawater, and said transducers are embedded in the explosive material in the focal plane of the lens.
 10. The device of claim 8 wherein the velocity of sound transmission in the explosive material is greater than in seawater, and the rear surface of the mass of explosive material is encased by a sound wave reflector having the configuration of an ellipsoid and the transducers are positioned in the focal plane of the reflector. 